Exclusion Criteria: Medical conditions. Subjects will not be eligible for the study based on the following criteria: (1) presence of acute or uncontrolled co-morbid medical conditions not limited to but including cardiovascular (e.g., history of acute coronary event, stroke, uncontrolled HTN) and neurological diseases (e.g., Parkinson's disease), as well as pain disorders; (2) presence of co-morbid inflammatory disorders such as Crohn's disease and ulcerative colitis and other autoimmune disorders; (3) presence of an uncontrolled medical condition that is deemed by the investigators to interfere with the proposed study procedures, or put the study participant at undue risk; (4) presence of chronic infections (e.g. positive purified protein derivative (PPD) test)) due to contraindication of tumor necrosis factor (TNF) antagonist use in these individuals and also because chronic infection can produce elevations in proinflammatory cytokines; (5) presence of an acute infectious illness in the two weeks prior to an experimental session; (6) pregnancy or breast-feeding because of the effects on neuroendocrine systems and sleep; (7) in women, the presence of vasomotor symptoms due to the effects of such symptoms on measures of sleep; (8) use of hormone containing medications including steroids; (9) current and/or regular use of nonsteroidal anti-inflammatory drug (NSAID) medications.